Crystal-size dependence of luminescence and absorption spectra of F(Br−) and F(F−) centers in BraFBr

Abstract Luminescence and absorption spectra of F(Br−) and F(F−) centers have been measured in various sizes of BaFBr crystals. Formation efficiency and the luminescence intensity of F(F−) were almost the same in all sizes of the crystals, while the intensity of the F(Br−) luminescence decreased with decreasing size. In the finest powdered crystal (used in image plates IP), the F(Br−) luminescence was not detected. Since the F(Br−) center is considered to be mobile at room temperature, RT, the nonexistence of the F(Br−) luminescence and the production of stable F(Br−) centers in the IP can be attributed to the pinning of the F(Br−) centers at the surface of the crystal.